LONDON — Four track and field events and 12 possible medals were up for grabs Wednesday night and Americans won seven of them.

Their big medal grab had the Americans crowing.

“It’s good to get some USA talk out here,’’ Brittney Reese, who won gold in the women’s long jump, said. “This means a lot to our country. We’re on track to get those 30 [track and field] medals we came here for. I think we’re the talk [of Olympic track and field].’’

The U.S. won three gold, two silver and two bronze medals.

Reese was joined by Allyson Felix in the women’s 200-meter and Aries Merritt in the men’s 110-meter hurdles with gold medals while Lashinda Demus took silver in the women’s 400-meter hurdles and Jason Richardson won silver in the men’s 110-meter hurdles and Janay Deloache won bronze in the women’s long jump and Carmelita Jeter won bronze in the women’s 200-meter.

“We come from a rich legacy and history and we wanted to do our part,’’ Felix said.

Despite her silver, Demus was devastated in defeat, crying at the finish line and later saying, “I feel like I let my country and my family down. I will not quit until I win gold. I’m definitely coming back in 2016. I’m already looking forward to 2016.’’

Capping the big night for the Americans were Ashton Eaton and Trey Hardee sitting at Nos. 1 and 2 through five events in the men’s decathlon, which will conclude with the final five events tonight.

“Tomorrow is going to be awesome,’’ Hardee said. “It would be special for me to get onto the podium.’’

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Caster Semenya, the South African who was subjected to gender testing after suspicions were raised several years ago, qualified for today’s women’s 800-meter semifinal, finishing behind American Alysia Johnson Montano in a time of 2:00.71. Montano clocked in at 2:00.44.

Nearly three years ago Semenya was forced to undergo a series of drug and gender tests after her win at the 2009 World Championships when her performance was questioned by officials, who raised doubts because of her muscular physique, running style and sudden improvement in times.

She was prevented from competing for almost a year before being cleared for competition.

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Usain Bolt and Jamaican teammate Yohan Blake each won their 200 semifinal heats. Bolt is trying to become the first man with two Olympic golds in the 200 meters.